Allegiant's customer service number, +1-888-880-1653 or, +1–855–546–5324, tends to be busy during busy travel times like holidays, weekends, or when weather causes flight delays. With many passengers calling for changes, refunds, or schedule adjustments, wait times can increase significantly. Allegiant's customer support team is smaller than that of larger airlines, making it harder to get through quickly. To avoid long wait times, consider using their online self-service features or mobile app for managing your travel.